Spatial Analysis of Commuting Behaviour: Evidence for Italy

The boost of the number of commuters affects several aspects of the local economy, and therefore a deep knowledge of the causes of this phenomenon is crucial in order to apply appropriate policies. A relevant question is: why do workers commute? One possible explanation is that commuting can be seen as a relevant spatial mechanism to equilibrate the imbalance between job demand and supply in the labour market. Under this perspective, it is worthy to investigate why length and frequency of home to work movements differ among areas. This research focuses on how much these differences depend on heterogeneity in the spatial features of the labour markets and it represents the first time that this kind of study is performed on the whole Italian territory. It can be relevant because Italy, compared to the countries depicted in the past, shows strong miscellaneous evidences in the average commuting length. The analysis is based on data from the XV Italian Population Census (year 2011) where, for each worker, the municipality of residence and the one of her workplace have been recorded. The individual observations have been aggregated in origin-destination matrices for each of the 611 Italian Travel To Work Areas seen as proxy of local labour markets. The empirical evaluation is developed through a two stages model built on the one proposed by Melo et al. (2011). The main idea is that the impedance parameter of a gravity model can be interpreted as a measure of how much an increase in the length of the trip is perceived by the worker as an obstacle in commuting. According to this intuition, areas with lower impedance are those where labour forces are less sensitive to raise in distance and tend to commute more. In the first stage, the impedance parameter is estimated for each labour market. The proposed measure of distance is the travel time, obtained with a GIS evaluation of the railway and road networks. In the second stage these estimates become the dependent variable of a new regression model, which uses selected spatial features of the labour market as regressors. Some of them are related to the shape of the area, others to the presence of agglomeration economies. Results show that, on average, Italian workers are very sensitive in increases in commuting distance. Indeed the estimated value of the impedance parameter is higher than in the literature. Finally it has been proved that both the shape of the labour market and the spatial distribution of jobs across it influence the average commuting distance. The results for the country are in line with the previous literature on other countries; commuting on average is longer in bigger labour markets, whereas tends to be shorter in more circular areas. On the other hand, an increase in urbanization economies and concentration of economic activities causes a reduction of the average length of the trips.